I really don't understand the island fixation that so many seem to have. Is it just accepted that non-island nations are incapable of policing their borders?
Sure, with actual army deployment we could get somewhere (it seems we have about 20 soldiers per kilometer of border). But the massive difference in effort between "police airports and the coast with radar" and "Mobilize the army" is huge.
The issue is not whether it's possible - it is - it's whether the cost of doing so is too high. It's a fair consideration to make, but it should be clear that that's the consideration being made, rather than pretending that only island nations have this option.